The non-impact, or ink jet recording method is becoming popular as a method for converting image data in the form of electrical signals into hard copies because less noise is produced during recording than by the impact method. The ink jet method is also considered particularly useful because ordinary paper can be used without the need for a special process, such as fixing, for recording purposes.
One ink jet method that has already been used comprises the steps of filling an airtight container with ink, applying a pressure pulse thereto, and sending the ink out of the orifice of the container in a jet for recording purposes. The ink jet recorder for this method cannot be made compact because of its operating mechanism, and the recorder requires mechanical scanning in order to record with a desired image density. This has caused the recording speed to be reduced.
Other techniques have been proposed for remedying shortcomings inherent in the ink jet method and making high-speed recording possible. The magnetic ink jet method is a typical example of an alternative method and comprises arranging magnetic ink close to a magnetic electrode array, forming an ink-jet state corresponding in position to a picture element by making use of a swell of the ink in the presence of a magnetic field, and jetting the magnetic ink in the static electric field. Since this method admits of electronic scanning, high-speed recording becomes possible, but it is still disadvantageous in that selection of ink is limited and the coloration characteristic of magnetic ink is often unsatisfactory.
Additionally, there is also known a so-called plane ink jet method, which comprises arranging ink in a slit-like inkholder in parallel to an electrode array, and jetting the ink in accordance with an electric field pattern formed between an electrode facing the electrode array through recording paper. Since no minute orifice for jetting ink is required in this method, the problem of ink clogging is minimized. However, high voltage applied for jetting the ink makes it necessary to drive the electrode array on a time division basis to prevent a voltage leak across adjoining or neighboring electrodes with the disadvantage that the recording speed is limited.
There has also been proposed the so-called heat bubble jet method for jetting ink out of an orifice by means of thermal energy. ln this method, ink bubbles are formed when the ink is abruptly heated to cause film boiling. A pressure rise resulting from the rapid formation of bubbles within the orifice is utilized to jet the ink. However, the film boiling temperatures are as high as 500.degree.-600.degree. C. and this makes it difficult to put this method to practical use because ink properties tend to vary with changes in temperature and because a protective layer provided over a heating resistor is deteriorated at elevated temperatures.
As set forth above, many problems remain to be solved in ink jet methods heretofore developed. The problems include difficulty in sufficiently increasing recording speed, the necessity of employing special ink and contriving a particular driving means, and thermal deterioration of the ink and the other elements of a recorder.